User's Manual

HARSFEN0602
The largest PTP motion available is XM/2 (or
30
2
if XM=0). This is since with modulo
calculations, the PTP motion will always go the short way. For example, if XM=1000, the
present position reference is 490, and the command PA=-490;BG is entered, then the
position reference will increase and go through 499 to –500 and then to –490. The total
length of the movement shall be 20 counts.
The parameters of PTP motion are summarized in the table below.
Parameter Action
AC
Acceleration in counts/
2
sec
DC
Deceleration in counts/
2
sec
SP Maximum speed in counts/sec
SF Smooth factor, in milliseconds
PR Relative position in counts
PA Specifies that the next motion shall be a PTP, and the absolute target position.
Table 12-5 – Parameter of PTP Motion
The PA command has more than one role. PA=n specifies that the next BG will start a PTP
motion. In addition, it specifies the target of the next PTP move.
When in the PTP mode, a BG command performs the following algorithm:
PA=PA+PR
Go to PA
PA is the absolute position target.
PR is the relative position target. The PR parameter enables the specification of an
incremental move, or a series of incremental moves. PR is reset to zero by the PA=n
command. Therefore, PA=n; BG initiates a motion towards n.
The value of PA is incremented automatically with PR every time a new motion is initiated.
For example, the sequence
PA=0;BG;while(MS==0);PR=1000;BG; while(MS==0);BG; while(MS==0);BG
Initiates four consecutive PTP motions, targeted to 0,1000,2000,and 3000 counts
respectively.
12.1.4.2 Example
The simplest point-to-point motion is from a stationary position to another stationary position.
The acceleration and the final speed limits are AC=100000,DC=200000,SP=2000.
We begin from PX=0 and command PA=70;BG
The speed graph shows the acceleration, constant speed, and deceleration state in the trajectory to the target.